Optical transmitter and optical transmitting apparatus using the same
a technology of optical transmitter and optical transmitting apparatus, applied in the field of optical transmitter, can solve the problems of affecting the communication of these devices, the circuit operation of the communication device, and the erroneous emission of light by the laser diode (ld)
Inactive Publication Date: 2005-08-02
OCLARO JAPAN INC
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Benefits of technology
Prevents erroneous optical signal output during power on / off operations, maintaining stable communication by ensuring no optical signal is emitted when the source voltage is low, and maintaining constant optical output power when voltage is normal.
Problems solved by technology
However, in the communication device having the above-mentioned related-art optical transmitter, the circuit operation in the communication device may be made unstable by the power on / off operation, causing the Laser diode (LD) to emit the light erroneously.
Consequently, if the communication device having the above-mentioned related-art type of optical transmitter is used in an optical transmission system based on PDS technology, the optical signal caused by erroneous light emission at a power on / off operation, affects the optical fibers of other communication devices through the optical divider / coupler, thereby interfering with the communication of these devices.
Method used
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[0023]The invention will be described in further detail by way of example with reference to the accompanying drawings.
[0024]Now, referring to FIG. 1, there is shown a basic configuration of an optical transmitter practiced as a first preferred embodiment of the present invention. As shown, the optical transmitter comprises a current source 1 for outputting a drive current, a Laser diode (LD) for generating an optical output signal based on the drive current, a modulator 9 for controlling the supply and cutoff of the drive current to the Laser diode (LD) according to a light-on / off signal (SG), a photodiode (PD) for converting part of the optical output signal into an electrical signal, an automatic power control circuit 2 for maintaining the optical power of the optical output signal at a constant level, a source voltage detector 3 for detecting that the source voltage is lower than a predetermined reference level, and a switch circuit 4 for controlling the current output of the cur...
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An optical transmitter for use in an optical transmitting system based on PDS (Passive Double Star) technology, does not erroneously output an optical signal when the optical transmitter is powered on / off. The optical transmitter has a current source 1 for outputting a drive current having a magnitude corresponding to an input control signal, a Laser diode (LD) for generating an optical output signal based on the received drive current, a modulator 9 for controlling the supply and cutoff of the drive current to the Laser diode (LD), a source voltage detector 3 for monitoring a source voltage to detect whether the source voltage is lower than a predetermined voltage, and a switch circuit 4 for outputting a control signal to the current source 1 to stop the supply of the drive current when the source voltage is determined to be lower than the predetermined voltage.
Description
[0001]This application is a divisional application of U.S. Ser. No. 09 / 247,809, tiled Feb. 11, 1999 now U.S. Pat. No. 6,559,997.FIELD OF THE INVENTION[0002]The present invention relates to an optical transmitter, and in particular, to an optical transmitter suitable for use in an optical transmitting system such as one based on PDS (Passive Double Star) technology.BACKGROUND OF THE INVENTION[0003]FIG. 12 shows a related-art type of optical transmitter. As shown, the optical transmitter is composed of a flip-flop circuit 106, a modulator 109, a Laser diode (hereinafter LD), a current source 101, a photodiode (PD), and an automatic power control circuit 102.[0004]The flip-flop circuit 106 captures a data signal DT in synchronization with a clock signal CL to output light-on / off signals (of positive phase and negative phase). A transistor Q1 and a transistor Q2 of the modulator 109 are supplied at the bases thereof with the positive-phase light-on / off signal and the negative-phase ligh...
Claims
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IPC IPC(8): H04B10/155H04B10/152H04B10/27H04B10/07H04B10/2507H04B10/272H04B10/293H04B10/54H04B10/564H04B10/572
CPCH04B10/504H04B10/564
Inventor TOKITA, SHIGERUHASEGAWA, ATSUSHIHAMAGISHI, TAKAHIRO
Owner OCLARO JAPAN INC